Exploding gas bubbles could destroy cancer

Exploding gas bubbles injected into the blood stream could provide a new way of destroying cancer cells in the body.

Engineers and cancer specialists at Leeds University are developing a new technique that uses microscopic gas bubbles to carry chemotherapy drugs to tumours where the drugs can target the cancer cells.

Each of the tiny bubbles, which are less than a tenth of the width of a human hair, can be specifically targeted to cancer cells so that they clump around the tumour.

A pulse of ultrasound then causes the gas inside the bubbles to vibrate until the bubble bursts and the resulting shock wave also punches small holes in the cancer cells allowing the drugs inside.

The researchers claim their technique will help to increase the effectiveness of chemotherapy treatments by targeting cancer directly while also cutting down on the harmful side effects caused by the toxic drugs when they attack healthy cells elsewhere in the body.

Professor Stephen Evans, who is leading the research at the university's department of physics, said they hoped to begin trialing the technology in animal models within the next three years before starting clinical trials in humans if it proves successful.

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He said: "By targeting the bubbles to the cancerous tissue, it means we can deliver far higher concentrations of drug to the tumour than is normally possible in chemotherapy.

"We are exploiting the physics of how the gas inside the bubbles responds when it is hit by a pulse of ultrasound."

Microbubbles, as they are known, are already used by doctors to help provide clearer images on ultrasound scans as they travel through the blood stream because the gas inside the bubble reflects the ultrasound pulse more effectively than the surrounding tissue.

Professor Evans and his colleagues, however, have found that by using specific frequencies of ultrasound energy, the gas inside the bubbles vibrates and eventually causes the bubbles to burst.

They have developed a way of using these bubbles to carry tiny capsules of drugs around the outside of the bubble, allowing it to carry the drugs through the blood stream to the tumour cells.

Antibodies that are specifically attracted to cancer cells are also placed on the outside of the bubbles to ensure they clump around the tumour rather than healthy tissue.

An ultrasound burst can then be used to burst the bubble, which also punches small holes into the cancer cells and makes it easier for the powerful drugs to get inside the cells.

Initially the researchers are developing the technique as a treatment for colorectal cancer but they hope it can be adapted to treat other cancers by changing the chemotherapy drug and the antibody on the outside of the bubble.

Dr Steve Freear, from the school of electronic engineering who is also working on the project, said: "Microbubbles are already considered to be safe in cardiology imaging.

"We are trying to use them as an vehicle to get drugs into the body safely so they don't cause harm to healthy cells. Most drugs used in chemotherapy are extremely toxic and kill cells, so we want to deliver them in a more targeted way."